WARSAW, May 15 (Reuters) - Poland’s KGHM, one of the world’s biggest copper and silver producers, reported a 38 percent slide in first-quarter net profit on Tuesday, hit by lower output and sales.

The state-run company said net profit for the first three months of the year stood at 439 million zlotys ($121.08 million), compared with the 453 million zlotys expected by analysts and 710 million zlotys reported a year ago.

KGHM’s standalone net profit, which reflects the company’s operations in Poland, fell 34 percent year on year to 530 million zlotys as electrolityc copper production declined by 15 percent. The group’s flagship oversees mining project, the Chilean Sierra Gorda mine, made a net loss of $66 million, little changed year on year because higher costs were offset by a revenue uplift from rising metal prices.

KGHM said the average copper price in the first quarter rose by 19 percent year on year. ($1 = 3.6258 zlotys)

Reporting by Agnieszka Barteczko
Editing by Marcin Goclowski and David Goodman